In a line selector which is used in this type of television image receiver, a vertical synchronizing signal itself is used as the start pulse of the counter. Once the timing at the tip end of the vertical synchronizing signal of the synchronizing detached circuit output is slipped out of timing in weak electric field, etc., the timing of the counter is slipped so that the number of given lines cannot be correctly counted, thus resulting in error actions. Furthermore, since they are separately provided independently, the cost is higher. Also, in a field distinguishing circuit, the vertical synchronizing pulse is detected by a logical circuit, and detection is adapted to be performed whether or not the horizontal synchronizing signal exists in a period of 1H or less from the last pulse of the equivalent pulses after the vertical synchronizing pulses. Thus, the entire circuit becomes complicated and the cost becomes higher. Recently IC is being progressed to simplify the construction of each circuit of the television image receiver. The line selector and the field distinguishing circuit or the compatible circuit of PAL and NTSC are desired to be formed of the IC through the combination with the vertical synchronizing circuit.
Accordingly, a first object of the present invention is to novelly provide a television image receiver provided with the vertical synchronizing circuit of a count down system (or count up system), wherein the line selector, the field distinguishing circuit or the compatible circuit of the PAL and the NTSC are formed of one IC as the simple construction, which is free from the defects of the conventional examples, lower in cost and higher in reliability.
A second object of the present invention is that in this type of television image receiver, the timing of the reset of the down counter of the vertical synchronizing circuit of the count system is specified and the down counter is commonly used in the line selector, whereby the line selector can be easily provided.
A third object of the present invention is that in this type of television image receiver, the logical product between the reset pulse to be provided from the down counter constituting the vertical synchronizing circuit and the horizontal synchronizing pulse, of given pulse width to be provided from the horizontal synchronizing circuit is drawn out to provide the field distinguishing pulse, whereby the field distinguishing circuit can be easily provided.
A fourth object of the present invention is that in this type of television image receiver, a decoder for decoding the output of the frequency dividing circuit is adapted to be switched to the each given vertical frequency with the PAL and the NTSC when the pulse of the horizontal frequency is counted and the vertical synchronization is effected, and the compatible circuit of the PAL and the NTSC can be easily provided.
A fifth object of the present invention is that in this type of television image receiver, the line selector and the field distinguishing circuit and the compatible circuit of the PAL and the NTSC together with the vertical synchronizing circuit of the count system are integrated in circuit through simple construction so that the superior capability can be exhibited.